In a conventional boiling water reactor, a nuclear reactor core is submerged in water inside an annular pressure vessel. An annular shroud or chimney extends upwardly from the reactor core for receiving therefrom a water-steam mixture which is channeled therein to a conventional steam separator assembly which separates the steam and water in a conventionally known manner. The steam separator assembly includes a plurality of conventional tubular steam separators each extending upwardly from a tubular standpipe, with the several standpipes extending upwardly from an annular head in the form of either a flat or dome plate disposed on the shroud or chimney. The standpipes are disposed in flow communication with respective holes through the head for receiving the water-steam mixture which is channeled upwardly into each of the steam separators.
The steam separator assembly is conventionally fixedly joined to the shroud by a plurality of circumferentially spaced apart bolts extending through an integral flange extending around the outer periphery of the head and into a mating support flange disposed at the top end of the shroud. In order to assemble or remove the steam separator assembly, each of the many bolts must be individually assembled and torqued or untorqued and disassembled from the head which requires a considerable amount of time. Since this operation is usually conducted manually with an operator positioned at the top of the pressure vessel, the operation is relatively complex and subjects the operator to radiation dosage from the reactor core.